An iris recognition system is an apparatus for identifying personal identity by distinguishing one's own peculiar iris pattern. The iris recognition system is superior in its accuracy in terms of the personal identification in comparison to the other biometric methods such as voice or fingerprint, and it has a high degree of security. The iris is a region existing between the pupil and the white sclera of an eye. The iris recognition method is a technique for identifying personal identities based on information obtained by analyzing respective one's own iris patterns different from each other.
Generally, the kernel technique of the iris recognition system is to acquire a more accurate eye image by using image acquisition equipment and to efficiently acquire unique characteristic information on the iris from the inputted eye image.
However, in a non-contact type human iris recognition system which acquires an iris image to be taken at a certain distance therefrom, the iris image with a variety of deformation may be acquired in practical. That is, it is unlikely that a complete eye image can be acquired since the eye is not necessarily directed toward a front face of a camera but positioned at a slight angle with respect to the camera. Thus, there may be a case where the information on an eye image rotated at an arbitrary angle with respect to a centerline of the iris is acquired.
Therefore, in order to solve the above problem produced in the process of image acquisition, it is necessary to accurately detect inner/outer boundaries of the iris from the eye image of a user and to normalize the iris image extracted from the eye image. However, conventional iris recognition methods have a problem in that they cannot accurately detect the inner/outer boundaries of the iris since upon detection of the boundaries, critical values are manually assigned to respective images after defining an arbitrary center of the pupil, or a mean value of the entire image is used as the critical value.
Furthermore, according to the conventional iris recognition system, since the normalization process of the iris image is not made or the correction to the rotated image is not considered, an incomplete eye image can be acquired if the eye is not directed toward the front face of the camera but positioned at a slight angle with respect to the camera, or a rotated iris image can be acquired due to movement of the user such as tilting of his/her head. Consequently, there were many cases where in spite of an iris image of the same user, the iris image may be falsely recognized as that of another user.